It's exactly like in English: • "The chicken's alive, is it?" (="...ĉu?") • "The chicken's alive, isn't it?" (="...ĉu ne?")
The first one expresses surprise that the chicken is still alive. The second sounds like someone who's pretty sure it's alive, and just wants confirmation.
Do not translate it in "google translate" Especially to Russian ))) https://translate.google.ru/#view=home&op=translate&sl=eo&tl=ru&text=La%20koko%20vivas%2C%20%C4%89u%3F